The invention relates to a set of movable contacts for a switch with a set of fixed contacts that comprises at least one pair of fixed contacts arranged a distance apart, comprising at least one contact element, a holder therefor and a resilient element, which contact element, when the switch is in the closed position, is in contact with the surface of the pair of fixed contacts under mechanical prestress producent by the resilient element and bridges the distance between the free end edges thereof facing one another, in which the holder body has a front and rear face running perpendicularly to the direction of movement thereof and side faces running perpendicularly to said front and rear faces and parallel to the direction of movement, in which a side face is provided with a longitudinal recess continuing to the end faces of the holder body for accommodating the contact element in such a way that the ends thereof protrude beyond the two end faces of the holder body.
A set of movable contacts of this type is disclosed in EP-B 0 281 622.
The known set of movable contacts comprises a number of contact elements in the form of a set of contact rollers. This set of contact rollers comprises an approximately T-shaped piece of iron, a resilient washer with corresponding counterpart and four contact rollers which partially bear on the resilient washers and partially are held together by clips. Between the rollers and the clips there is a spacer which has a thickness which is somewhat less than the thickness of the fixed contacts of the switch. The parts are all provided with an elongated slot to allow the leg of the T-shaped piece of iron to pass through. There is a spiral spring on top of the last resilient washer and the complete device is held together by a retaining plate that is equipped to be pressed downwards over the T-shaped leg and then to be turned through approximately 90xc2x0. The mid spacer is furthermore provided with projections which interact with means on a drive disk that can be moved.
The holder of the set of movable contacts for holding the contact elements or rollers in place consists of a large number of separate components, so that a large number of operations are needed when assembling the set of movable contacts.
The aim of the invention is to provide a set of movable contacts of the type mentioned below with which the number of components is restricted to a minimum and the assembly of which is simpler and with which only a small number of operations is required for assembly. minimum and the assembly of which is simpler and with which only a small number of operations is required for assembly.
Said aim is achieved according to the invention in that the the resilient element is arranged such that it encloses the contact element in interaction with the longitudinal recess in the holder and holds the contact element in the longitudinal recess.
The resilient element serves not only to produce the contact pressure of the contact element on the fixed contact but also serves to enclose the contact element in interaction with the longitudinal recess in the holder. There is thus only a holder in one piece and a resilient element for prestressing and holding in place one or more contact elements.
British Patent Specification 763,245 describes a set of movable contacts for a switch with a set of fixed contacts that comprises at least one pair of fixed contacts arranged a distance apart, comprising at least one contact element, a holder therefor and a resilient element, which contact element, when the switch is in the closed position, is in contact with the surface of the pair of fixed contacts under mechanical prestress produced by the resilient element and bridges the distance between the free end edges thereof facing one another, in which the holder body has a front and rear face running perpendicularly to the direction of movement thereof and side faces running perpendicularly to said front and rear faces and parallel to the direction of movement, in which a side face is provided with a longitudinal recess continuing to the end faces of the holder body for accommodating the contact element in such a way that the ends thereof protrude beyond the two end faces of the holder body.
If the holder is considered separately, the contact elements are pushed out the corresponding recess in the holder body. There is no form-fitting unit of holder body, resilient element and contact elements.
If the holder is made of plastic, the side face of the longitudinal recess closest to the rear face of the holder can be provided with a bearer element. In the absence of the bearer element, which can be in the form of a plate, the contact element exerts high forces on the said side face of the longitudinal recess when the switch is closed, so that said side face can deform and the switching characteristics of the set of movable contacts can be adversely affected. This deformation is counteracted by the bearer element in that the said forces are distributed over a larger surface on the said side face.
In one embodiment of the invention the holder is provided with a second continuous longitudinal recess on the other side face for accommodating a second contact element and the front face of the holder body is provided with a transverse recess, running transversely to the continuous recesses, for accommodating a U-shaped resilient element consisting of two arms and a base joining these, the side walls of the transverse recess being some distance away from the end faces of the holder body and the base of the U bearing on the bottom of the transverse recess and the arms thereof engaging around the outsides of the contact elements.
With this embodiment as well a form-fitting unit with very few components is provided.
Preferably, the bottom of the transverse recess is lower than the side walls of the longitudinal recesses closest to the rear wall of the holder body, the difference in depth not being greater than the thickness of the base of the resilient element.
With this embodiment the base of the resilient element advantageously ensures the distribution of the forces of the contact elements on the side face of the longitudinal recess closest to the rear face of the holder and as it were replaces the abovementioned plate of hard material.